The present invention relates to a substrate transport method and apparatus for transporting a substrate to a processing section to clean the surface of the substrate, and also relates to a substrate processing system having the substrate transport apparatus.
In a photolithographic process of manufacturing the semiconductor devices, it is very important to maintain the surface of the wafer clean. This is because if contaminants, such as particles, organic substances, and metallic ions, are attached to the surface of the semiconductor wafer, they significantly defect a circuit pattern of the semiconductor device. Therefore, in the photolithographic process, the wafer surface is usually washed when necessary. The contaminants are removed from the wafer surface, for example, by rubbing the wafer surface by a brush while a chemical washing solution is poured thereon. Such a washing treatment is usually carried out in a washing apparatus equipped with a spin chuck and a rotatory brush.
As shown in FIG. 1, a conventionally used substrate processing system 100 has a processing section 104 for washing the surface of the wafer with a chemical solution and drying it, and a substrate transporting arm mechanism 105 for transporting the wafer W to the processing section 104. The processing section 104 has three processing units 101, 102, 103. The substrate transport apparatus 105 has three arms 106a, 106b, 106c. The processing units 101, 102, 103 have loading/unloading ports 101a, 102a, 103a, respectively. The wafer W is loaded/unloaded into/from units 101, 102, 103 through the loading/unloading ports 101a, 102a, 103a, respectively.
The substrate transport apparatus. 105 has an X-axis driving mechanism for moving an arm portion 106 in an X-axis direction, a Z-axis driving mechanism 107 for moving the arm portion 106 in a Z-axis direction, a xcex8-axis driving mechanism for rotating the arm portion 106 around the Z-axis, and a back-and-forth moving mechanism for moving each of arms 106a, 106b, 106c back and forth. The Z-axis driving mechanism 107 has a single ball screw 110 whose rotation movement is driven by a motor 109. The motor 109 and the ball screw 110 are surrounded by a cover 108 in the expandable bellows form.
However, when the Z-axis driving mechanism 107 is used for a long time, particles are sometimes generated from the cover 108 in the form of bellows, attaching onto the wafer W.
Furthermore, as shown in FIG. 2, the vertical opening length of the loading/unloading port 101a in the conventional apparatus is larger than the vertical size of an assembly of three arms 106a, 106b, 106c. Thus, the particles are likely to enter the processing unit 101 when the wafer W is loaded/unloaded. In addition, a shutter 130 is moved in a long distance and thus long time is required to open/shut the loading/unloading port 101a. As a result, throughput of the treatment decreases. Furthermore, it take long time to exchange the first arm 106a arranged at the uppermost stage and the third arm 106c arranged at the lowermost stage, with the result that the throughput decreases.
An object of the present invention is to provide a substrate transporting method and apparatus, and a substrate processing system capable of reducing time required,for loading and unloading a substrate into/from a processing unit, thereby improving the throughput.
Another object of the present invention is to provide a substrate transport apparatus having a driving mechanism which does not allow the particles to leak outside.
According to the present invention, there is provided a method of transporting a substrate by using a substrate transport apparatus which comprises:
first, second, and third arms arranged vertically in multiple stages,
a plurality of processing units each having a load/unload port for loading/unloading the substrate,
the method comprising:
(a) inputting data of processing conditions for processing the substrate;
(b) determining whether a number of processing units required for processing the substrate is an odd number or an even number;
(c1) when a determination result of the step (b) is an odd number,
transporting the substrate, in accordance with the following steps (d1) to (i1):
(d1) taking out the substrate by the second arm from a substrate loading/unloading section;
(e1) loading the substrate by the second arm to an odd-numbered processing unit;
(f1) unloading the substrate by the third arm from an odd-numbered processing unit; except for a final processing unit;
(g1) loading the substrate by the third arm to an even-numbered processing unit;
(h1) unloading the substrate by the second arm from an even-numbered processing unit; and
(i1) unloading the substrate from the final processing unit by the first arm and loading the substrate by the first arm into the substrate loading/unloading section; and
(c2) when a determination result of the step (b) is an even number,
transporting the substrate, in accordance with the following steps (d2) to (i2);
(d2) taking out the substrate by the third arm from the substrate loading/unloading section;
(e2) loading the substrate by the third arm into an odd-numbered processing unit;
(f2) unloading the substrate by the second arm from an odd-numbered processing unit;
(g2) loading the substrate by the second arm into an even-numbered processing unit;
(h2) unloading the substrate by the third arm from an even-numbered processing unit except for a final processing unit; and
(i2) unloading the substrate by the first arm from the final processing unit and loading the substrate by the first arm into the substrate loading/unloading section.
Note that a second substrate to be used next may be taken out from the substrate loading/unloading section in advance by the second arm during a period from the step (e1) to (f1).
Furthermore, the second substrate may be unloaded from an odd-numbered processing unit in advance by the third arm during a period from the step (g1) to (h1).
Moreover, the second substrate may be taken out from the substrate loading/unloading section in advance by the third arm during a period from the step (e2) to (f2).
Still further, the second substrate may be unloaded from an odd-numbered processing unit in advance during a period from the step (g2) to (h2).
According to the present invention, there is provided a substrate processing system comprising:
a substrate loading/unloading section for receiving a plurality of substrates and sending out the substrates sequentially one by one;
a processing section having a plurality of processing units each having a loading/unloading port for loading and unloading the substrates;
a substrate transport apparatus which has first, second, and third arms arranged movable between the substrate loading/unloading section and the processing section and set vertically in multiple stages, and which has an arm back-and-forth moving mechanism for moving each of the first, second, and third arms, back and forth;
a control section for controlling an operation of the substrate transport apparatus; and
data input means for inputting data of processing conditions for processing the substrate into the control section.
The control section controls the substrate transport apparatus by
determining whether a number of processing units required for processing the substrate is an odd number or an even number on the basis of the data of processing conditions;
when a determination result is an odd number,
taking out the substrate, by the second arm, from the substrate loading/unloading section;
loading the substrate by the second arm to an odd-numbered processing unit,
unloading the substrate by the third arm from an odd-numbered processing unit except for a final processing unit;
loading the substrate by the third arm to an even-numbered processing unit;
unloading the substrate by the second arm from an even-numbered processing unit;
unloading the substrate by the first arm from the final processing unit; and further
loading the substrate by the first arm into the substrate loading/unloading section; and
when the determination result is an even number,
taking out the substrate, by the third arm, from the substrate loading/unloading section;
loading the substrate by the third arm to an odd-numbered processing unit;
unloading the substrate by the second arm from an odd-numbered processing unit;
loading the substrate by the second arm from an even-numbered processing unit;
unloading the substrate by the third arm from an even-numbered processing unit except for a final processing unit;
unloading the substrate by the first arm from the final processing unit; and further
loading the substrate by the first arm into the substrate loading/unloading section.
The substrate transport apparatus comprises:
a xcex8 rotation driving mechanism for rotating by an angle of xcex8 around each of vertical axes of the first, second, and third arms;
an arm back-and-forth moving mechanism for moving each of the first, second, and third arms, back and forth;
a Z-axis driving mechanism for moving the first, second, and third arms in the Z-axis direction; and
a cover assembly consisting of a plurality of slide covers surrounding the Z-axis driving mechanism and slidably assembled with each other, a diameter of an upper slide cover being larger than a diameter of a lower slide.
In this case, it is preferable that the cover assembly be formed by concentrically assembling a plurality of cylindrical slide covers.
Further in this case, it is preferable that the loading/unloading port of the processing unit be sufficiently large to load and unload two arms of the first, second, third arms.
According to the present invention, there is provided a substrate transport apparatus for transporting substrates from a substrate loading/unloading section to a processing section sequentially one by one, comprising:
a plurality of arms for holding a substrate;
a xcex8 rotation driving mechanism for rotating the plurality of arms simultaneously around a vertical axis by an angle of xcex8;
an arm back-and-forth moving mechanism for moving each of the plurality of arms, back and forth;
a Z-axis driving mechanism for moving the plurality of arms, simultaneously up and down; and
a cover assembly surrounding the Z-axis driving mechanism in order to shut out the Z-axis driving mechanism from an outer atmosphere, the cover assembly consisting of a plurality of cylindrical slide covers slidably assembled concentrically,
in which, when the plurality of arms are moved up by the Z-axis driving mechanism, an outer slide cover slidably moves to an inner slide cover, with the result that the outer slide cover is located above the inner slide cover.
The cover assembly comprises:
an unmovable slide cover member which is not driven by up-and-down movement of the Z-axis driving mechanism and thus maintained unmoved;
a first movable slide cover slidably driven by the up-and-down movement of the Z-axis driving mechanism, relative to the unmovable slide cover; and
a second movable slide cover slidably driven by the up-and down movement of the Z-axis driving mechanism, relative to the first movable slide cover.
It is preferable that the Z-axis driving mechanism comprise:
a first ball screw mechanism for moving the first movable slide cover up and down to the unmovable slide cover; and
a second ball screw mechanism for moving the second movable slide cover up and down to the first movable slide cover.
In this case, it is preferable that the first ball screw mechanism comprise:
an unmovable support member connected to the unmovable slide cover;
a first ball screw fixed to the unmovable support member;
a first nut engaged with the first ball screw;
a belt hanging around the first nut; and
a common motor for transmitting rotatory driving force to the belt; and
the second ball screw mechanism comprises:
a first movable support member connected to the first movable support member;
a second movable support member connected to the second movable slide cover;
a second nut engaged with the second ball screw and fixed to the second movable support member; and
a pulley having the belt hung thereon and fitted to a lower portion of the second ball screw.
Furthermore, the Z-axis driving mechanism may comprise:
a first rack/pinion mechanism for moving the first movable slide cover up and down to the unmovable slide cover; and
a second rack/pinion mechanism for moving the second movable slide cover up and down to the first movable slide cover.
In this case, it is preferable that the first rack/pinion mechanism comprise:
a first rack fixed on the unmovable slide cover;
a common pinion engaged with the first rack; and
a common motor for transmitting rotatory driving force to the common pinion, and
the second rack/pinion mechanism comprises:
a second movable support member connected to the second movable slide cover; and
a second rack fitted to the second movable support member and engaged with the common pinion.
According to the present invention, it is possible to reduce time for loading/unloading the substrate into/from the processing unit. The opening area of the loading/unloading port is reduced. It is therefore possible to prevent an inner atmosphere of the process unit containing chemical substances from being dispersed into an outer atmosphere and to suppress particles from being introduced into the inside the process unit to minimum.
Regardless the number of the processing units, namely, odd number or even number, the arm portion may be moved only by the distance corresponding to two steps in the final processing unit. Therefore, the throughput is increased and the durability of the substrate transport apparatus is improved. As a result, energy saving of the substrate processing system is successfully attained.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.